Stuffing box for an artificial lift system

ABSTRACT

A stuffing box for an artificial lift system includes a primary housing having threads. The stuffing box also includes at least one primary seal disposed within the primary housing, in which the at least one primary seal is configured to engage a polish rod. The stuffing box includes a secondary housing having threads. The stuffing box also includes at least one secondary seal disposed within the secondary housing, in which the at least one secondary seal is configured to engage the polish rod. The threads of the secondary housing are configured to engage the threads of the primary housing to couple the secondary housing to the primary housing, and the secondary housing is configured to compress the at least one primary seal via rotation of the secondary housing relative to the primary housing while the threads of the secondary housing are engaged with the threads of the primary housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of U.S. Provisional Application Ser. No. 63/146,880, entitled “STUFFING BOX FOR AN ARTIFICIAL LIFT SYSTEM”, filed Feb. 8, 2021, which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates generally to a stuffing box for an artificial lift system.

Wells are drilled into reservoirs to discover and produce oil. The oil within such a reservoir may be under sufficient pressure to drive the oil through the well to the surface. However, over time, the natural pressure of the oil may decline, and an artificial lift system may be used to extract the oil from the reservoir. The artificial lift system may include a pump disposed within the reservoir and a wellhead at the surface. A tubing string may be supported by the wellhead and may extend to the reservoir, and the pump may drive the oil from the reservoir to the wellhead via the tubing string.

The pump is driven by a series of polish rods that extend through the wellhead and the tubing string to the pump. The polish rods are lifted and lowered by a pump jack, which supports the polish rods. In addition, the wellhead includes a stuffing box configured to establish a seal around a polish rod at the end of the series of polish rods, thereby substantially blocking flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. The stuffing box includes a primary housing configured to house one or more primary seals and a secondary housing configured to house one or more secondary seals. The primary seals are compressed by a primary cap that is coupled to the primary housing by a threaded connection, and the secondary seals are compressed by a secondary cap that is coupled to the secondary housing by a threaded connection. In addition, the secondary housing is positioned above the primary housing and coupled to the primary housing by a threaded connection. Because the secondary housing is positioned above the primary housing, the stuffing box may have a substantial vertical extent, thereby increasing the stroke length of the pump jack.

BRIEF DESCRIPTION

In certain embodiments, a stuffing box for an artificial lift system includes a primary housing having threads. The stuffing box also includes at least one primary seal disposed within the primary housing, in which the at least one primary seal is configured to engage a polish rod. In addition, the stuffing box includes a secondary housing having threads. The stuffing box also includes at least one secondary seal disposed within the secondary housing, in which the at least one secondary seal is configured to engage the polish rod. The threads of the secondary housing are configured to engage the threads of the primary housing to couple the secondary housing to the primary housing, and the secondary housing is configured to compress the at least one primary seal via rotation of the secondary housing relative to the primary housing while the threads of the secondary housing are engaged with the threads of the primary housing.

DRAWINGS

These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic side view of an embodiment of an artificial lift system having a wellhead;

FIG. 2 is a schematic side view of a portion of the artificial lift system of FIG. 1, including the wellhead and a polish rod connection assembly;

FIG. 3 is a perspective view of an embodiment of a stuffing box that may be employed within the wellhead of FIG. 1; and

FIG. 4 is a cross-sectional view of the stuffing box of FIG. 3.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments.

FIG. 1 is a schematic side view of an embodiment of an artificial lift system 10 having a wellhead 12. As illustrated, the artificial lift system 10 includes a pump 14 disposed within a reservoir 16. In addition, the wellhead 12 is positioned at the surface 18. A tubing string 20, which is supported by the wellhead 12, extends from the surface 18 to the reservoir 16. The pump 14 is configured to drive oil from the reservoir 16 to the surface 18 via the tubing string 20 and the wellhead 12.

The pump 14 is driven by a series of polish rods that extend through the tubing string 20 to the pump 14. As illustrated, a polish rod 22 at the end of the series of polish rods is coupled to a pump jack 24 of the artificial lift system 10. The pump jack 24 is configured to lift and lower the polish rods, thereby driving the pump 14. One or more polish rods may contact the tubing string 20 at one or more points along a circumference of the polish rod(s). Accordingly, as the polish rods are driven to move within the tubing string 20, certain point(s) on the polish rod(s) may wear. In the illustrated embodiment, a rod rotator assembly 26 is configured to drive the polish rods to rotate within the tubing string 20, thereby distributing the wear around the circumference of the polish rod(s). As a result, the longevity of the polish rods may be increased. As discussed in detail below, the rod rotator assembly 26 is supported by a carrier (e.g., carrier bar) that is supported by the pump jack 24 via one or more cables. For example, the rod rotator assembly 26 may include a housing supported by the carrier of the artificial lift system 10. In addition, the rod rotator assembly 26 may include a top cap configured to rotate relative to the housing, in which the top cap is configured to support the polish rods (e.g., via polish rod clamp(s) coupled to the polish rod 22).

Furthermore, as discussed in detail below, the wellhead 12 includes a stuffing box configured to establish a seal around the polish rod 22 that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. In certain embodiments, the stuffing box includes a primary housing having internal threads, and the stuffing box includes one or more primary seals disposed within the primary housing, in which the primary seal(s) are configured to engage the polish rod 22. The stuffing box also includes a secondary housing having external threads. The external threads of the secondary housing are configured to engage the internal threads of the primary housing to couple the secondary housing to the primary housing, and the secondary housing is configured to compress the primary seal(s) via rotation of the secondary housing relative to the primary housing while the external threads of the secondary housing are engaged with the internal threads of the primary housing. In addition, the stuffing box includes one or more secondary seals disposed within the secondary housing, in which the secondary seal(s) are configured to engage the polish rod 22. The stuffing box also includes a cap coupled to the secondary housing and configured to compress the secondary seal(s). Because the secondary housing is configured to compress the primary seal(s), a separate cap for compressing the primary seal(s) is obviated, thereby reducing the vertical extent of the stuffing box. As a result, the stroke length of the pump jack may be reduced.

FIG. 2 is a schematic side view of a portion of the artificial lift system 10 of FIG. 1, including the wellhead 12 and a polish rod connection assembly 28. In the illustrated embodiment, the wellhead 12 includes a tubing spool 30 that supports the tubing string (e.g., via a tubing hanger coupled to an end of the tubing string and engaged with the tubing spool). The wellhead 12 also includes a pumping tee 32 coupled to the tubing spool 30 and to a flowline 34. The pumping tee 32 is configured to receive oil from the tubing spool 30 and to control flow of the oil through the flowline 34. The flowline 34 may extend to a storage or processing facility. Furthermore, the wellhead 12 includes a stuffing box 36 coupled to the pumping tee 32. As previously discussed, the stuffing box is configured to establish a seal around the polish rod 22 that substantially blocks flow of oil through the polish rod/stuffing box interface while enabling the upward/downward movement of the polish rods. While the wellhead 12 includes the tubing spool 30, the pumping tee 32, and the stuffing box 36 in the illustrated embodiment, the wellhead may include other and/or additional components in other embodiments.

The polish rod connection assembly 28 includes the rod rotator assembly 26, which is configured to drive the polish rods to rotate relative to the wellhead 12 and the tubing string. The polish rod connection assembly 28 also includes a carrier 38 (e.g., carrier bar) configured to support the rod rotator assembly 26. The carrier 38 may be coupled to the pump jack by one or more cables. In addition, the polish rod connection assembly 28 includes one or more polish rod clamps 40 configured to non-movably couple to the polish rod 22. The polish rod clamps 40 transfer the load (e.g., substantially vertical load) of the polish rods to the rod rotator assembly 26, the load flows through the rod rotator assembly 26 to the carrier 38, and the load applied to the carrier is transferred to the pump jack via the cable(s). Accordingly, during an upward movement of the pump jack, the pump jack lifts the carrier 38 via the cable(s), the carrier 38 drives the rod rotator assembly 26 to move upwardly, and the rod rotator assembly 26 drives the polish rods to move upwardly via engagement of the rod rotator assembly 26 with the polish rod clamp(s) 40. During a downward movement of the pump jack, the pump jack drives the polish rod 22 downwardly. Because the polish rod clamp(s) 40 are non-movably coupled to the polish rod 22, the polish rod clamp(s) 40 drive the rod rotator assembly 26 to move downwardly, thereby driving the carrier 38 to move downwardly.

FIG. 3 is a perspective view of an embodiment of a stuffing box 36 that may be employed within the wellhead of FIG. 1. In the illustrated embodiment, the stuffing box 36 includes a primary housing 42 and a secondary housing 44 engaged with the primary housing 42. The primary housing 42 has external threads 46 configured to engage corresponding internal threads of the pumping tee to couple the stuffing box 36 to the pumping tee. While the primary housing 42 is coupled to the pumping tee with a threaded connection in the illustrated embodiment, in other embodiments, the primary housing may be coupled to the pumping tee by any other suitable type(s) of connection(s) (e.g., alone or in combination with the threaded connection), such as fastener connection(s), pinned connection(s), adhesive connection(s), other suitable type(s) of connection(s), or a combination thereof.

Furthermore, as discussed in detail below, the primary housing 42 has internal threads, and the secondary housing 44 has external threads. The external threads of the secondary housing 44 are configured to engage the internal threads of the primary housing 42 to couple the secondary housing 44 to the primary housing 42. In the illustrated embodiment, the secondary housing 44 has one or more flat surfaces 48 configured to interface with a tool (e.g., wrench, etc.), thereby enabling the tool to drive the secondary housing 44 to rotate relative to the primary housing 42. While the internal threads of the primary housing 42 are engaged with the external threads of the secondary housing 44, rotation of the secondary housing 44 relative to the primary housing 42 drives the secondary housing 44 to move toward the primary housing 42 along a longitudinal axis 50 of the stuffing box 36. While the secondary housing 44 has flat surface(s) 48 in the illustrated embodiment, in other embodiments, the secondary housing may include other suitable structure(s) configured to engage a corresponding tool for driving the secondary housing to rotate (e.g., alone or in combination with the flat surface(s)), such as one or more recesses, an elliptical surface, curved/rounded surface(s), other suitable structure(s), or a combination thereof. While driving the secondary housing to rotate with a tool is disclosed above, in certain embodiments, the secondary housing may be driven to rotate by hand. In such embodiments, the structure(s) configured to interface with the tool may be omitted.

As discussed in detail below, the stuffing box 36 includes one or more primary seals disposed within the primary housing 42, and each primary seal is configured to engage the polish rod at the end of the series of polish rods. The secondary housing 44 is configured to compress the primary seal(s) via rotation of the secondary housing 44 relative to the primary housing 42 while the external threads of the secondary housing 44 are engaged with the internal threads of the primary housing 42. For example, a target torque may be applied to the secondary housing 44 to establish a target compression of the primary seal(s). In addition, the stuffing box 36 includes one or more secondary seals disposed within the secondary housing, and each secondary seal is configured to engage the polish rod at the end of the series of polish rods. The stuffing box 36 also includes a cap 52 coupled to the secondary housing 44 and configured to compress the secondary seal(s). In the illustrated embodiment, the stuffing box 36 includes one or more fastener(s) 54 (e.g., bolt(s), screw(s), etc.) configured to couple the cap 52 to the secondary housing 44 and to drive the cap 52 along the longitudinal axis 50 toward the secondary seal(s), thereby driving the cap 52 to compress the secondary seal(s). For example, a target torque may be applied to each fastener 54 to establish a target compression of the secondary seal(s). While the cap 52 is coupled to the secondary housing 44 with fastener(s) 54 in the illustrated embodiment, in other embodiments, the cap may be coupled to the secondary housing via a threaded connection (e.g., such that rotation of the cap relative to the secondary housing compresses the secondary seal(s)).

As illustrated, a passage 56 extends through an entire extent of the stuffing box 36 along the longitudinal axis 50. During operation of the artificial lift system, the polish rod may move upwardly and downwardly through the passage, and the primary and secondary seals may engage the polish rod. The primary and secondary seals are configured to substantially block flow of oil through the polish rod/stuffing box interface while enabling the polish rod to move upwardly and downwardly. Because the secondary housing 44 is configured to compress the primary seal(s), a separate cap for compressing the primary seal(s) is obviated, thereby reducing the vertical extent of the stuffing box. As a result, the stroke length of the pump jack may be reduced.

As discussed in detail below, the primary housing 42 has one or more apertures extending from an interior cavity of the primary housing 42 to an exterior surface 58 of the primary housing 42 along a radial axis 60 of the stuffing box 36. The interior cavity is positioned between the primary seal(s) and the secondary seal(s). Accordingly, oil that bypasses the primary seal(s) may flow into the interior cavity and through the aperture(s). In addition, the stuffing box 36 includes an adapter ring 62 disposed about the primary housing 42 and aligned with the aperture(s) along the longitudinal axis 50 of the stuffing box 36. The adapter ring 62 has a port 64 extending through the adapter ring 62 along the radial axis 60, and the adapter ring 62 is configured to rotate relative to the primary housing 42, thereby enabling the port 64 to be positioned at any desired location along a circumferential axis 66 of the stuffing box 36. In the illustrated embodiment, a plug 68 is disposed within the port 64. However, the plug 68 may be removed to facilitate fluidly coupling the port to a suitable device (e.g., oil collection container, oil sensor(s), etc.). As discussed in detail below, at least one gasket may be disposed above the aperture(s) and at least one gasket may be disposed below the aperture(s), in which each gasket is engaged with the exterior surface 58 of the primary housing 42 and the adapter ring 62. Accordingly, any oil that bypasses the primary seal(s) and flows through the aperture(s) is directed through the port 64 (e.g., to the oil collection container, to the oil sensor(s), etc.), thereby enabling an operator or an automated system to detect the quantity/rate of oil flow through the primary seal(s). If the quantity/rate of oil flow through the primary seal(s) is greater than a threshold quantity/rate, the compression of the primary seal(s) may be increased or the primary seal(s) may be replaced.

In the illustrated embodiment, the primary housing 44 has a shoulder configured to engage the adapter ring 62 to align the adapter ring 62 with the aperture(s) along the longitudinal axis 50 of the stuffing box 36. The shoulder is configured to block movement of the adapter ring 62 in a downward direction along the longitudinal axis 50. In addition, a retaining ring 70 may be engaged with a recess in the primary housing 42 to block upward movement of the adapter ring 62 (e.g., away from the shoulder) along the longitudinal axis 50. While the adapter ring 62 is rotatably coupled to the primary housing 42 by a lower shoulder and an upper retaining ring 70 in the illustrated embodiment, in other embodiments, the adapter ring may be rotatably coupled to the primary housing by any other suitable connection(s) (e.g., an upper shoulder and a lower retaining ring, upper and lower retaining rings, etc.). Because the port 64 is disposed along the primary housing 42, the height of the stuffing box 36 may be reduced (e.g., as compared to a stuffing box in which the port extends through the secondary housing at a position above the primary housing), thereby reducing stroke length of the pump jack. In addition, the reduced height of the stuffing box may increase the tolerance of angular misalignment between the polish rod and the stuffing box, thereby facilitating operation of the artificial lift system. Furthermore, because the port 64 may be positioned at any suitable location along the circumferential axis 66, a line that extends from the port 64 (e.g., to the oil collection container, to the oil sensor(s), etc.) may be positioned to avoid other components surrounding the stuffing box 36, thereby facilitating formation of the wellhead.

FIG. 4 is a cross-sectional view of the stuffing box 36 of FIG. 3. As previously discussed, the primary housing 42 has internal threads 72, and one or more primary seals 74 are disposed within the primary housing 42. In the illustrated embodiment, the stuffing box 36 has three primary seals 74. However, in other embodiments, the stuffing box 36 may have more or fewer primary seals 74 (e.g., 1, 2, 4, 5, 6, or more). Each primary seal 74 has an annular shape and extends about the internal circumference of the primary housing 42, and each primary seal is configured to engage the polish rod at the end of the series of polish rods. In addition, each primary seal 74 may be formed from any suitable material (e.g., polymeric material, rubber, etc.) and configured to expand along the radial axis 60 in response to compression along the longitudinal axis 50. In certain embodiments, each primary seal 74 is formed as a single annular piece configured to extend about the internal circumference of the primary housing 42. However, in other embodiments, at least one primary seal may be formed from multiple circumferential elements that collectively form the annular primary seal.

Furthermore, as previously discussed, the secondary housing 44 has external threads 76 configured to engage the internal threads 72 of the primary housing 42 to couple the secondary housing 44 to the primary housing 42. The secondary housing 44 is configured to compress the primary seal(s) 74 via rotation of the secondary housing 44 relative to the primary housing 42 while the external threads 76 of the secondary housing 44 are engaged with the internal threads 72 of the primary housing 42. For example, a tool may engage the flat surfaces 48 of the secondary housing 44 and apply a target torque to the secondary housing 44 to establish a target compression of the primary seal(s) 74 (e.g., in which the target compression establishes a target radial contact force between the primary seal(s) and the polish rod).

In the illustrated embodiment, two first annular rings 78 are positioned between an engagement surface 79 of the secondary housing 44 and the primary seal(s) 74 along the longitudinal axis 50. The first annular rings 78 are configured to function as bushings that facilitate rotation of the secondary housing 44 while enabling the secondary housing 44 to apply a sufficient force to the primary seal(s) to compress the primary seal(s) to the target compression. Each first annular ring 78 may be formed from any suitable material (e.g., brass, a polymeric material, etc.), and each first annular ring may be formed from any suitable number of circumferential elements (e.g., 1, 2, 3, 4, or more). Furthermore, while the stuffing box 36 includes two first annular rings 78 in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer first annular rings (e.g., 0, 1, 3, 4, or more). For example, in certain embodiments, the first annular rings may be omitted. In such embodiments, the engagement surface of the secondary housing may be formed from a material (e.g., polymeric material, etc.) that facilitates rotation of the secondary housing relative to the primary seal(s).

In the illustrated embodiment, the stuffing box 36 includes a flapper assembly 80 disposed within the primary housing 42 and positioned below the primary seal(s) 74 along the longitudinal axis 50. The flapper assembly 80 includes a flapper carrier 82 and a flapper 84 pivotally coupled to the flapper carrier 82. The flapper 84 is biased toward the flapper carrier 82 (e.g., via a coil spring, etc.). Accordingly, while the polish rod is not disposed within the passage 56 through the stuffing box 36, the flapper 84 may be driven to rotate to a closed position, in which the flapper 84 engages the flapper carrier 82, to substantially block oil flow through the passage 56. In addition, while the polish rod is disposed within the passage 56 (e.g., during operation of the artificial lift system), the polish rod may block the flapper 84 from rotating to the closed position, thereby maintaining the flapper 84 in an open position. As previously discussed, the flapper carrier 82 is positioned below the primary seal(s) 74 along the longitudinal axis 50. Downward movement of the flapper carrier 82 along the longitudinal axis 50 is blocked by an internal shoulder 86 of the primary housing 42 (e.g., which engages the flapper carrier). Accordingly, the primary seal(s) 74 are compressed between the secondary housing 44 and the flapper carrier 82. In certain embodiments, the flapper carrier 82 is not rigidly coupled to the primary housing (e.g., the flapper assembly may be inserted into the primary housing and moved to the illustrated installed position without restriction during assembly of the stuffing box). However, in other embodiments, the flapper carrier may be coupled to the primary housing by suitable connection(s) (e.g., a threaded connection, pinned connection(s), fastener connection(s), etc.). In such embodiments, the internal shoulder of the primary housing may be omitted. Furthermore, in the illustrated embodiment, test ports (e.g., apertures extending through the primary housing 42) are positioned above and below the flapper 84 along the longitudinal axis 50. However, in other embodiments, at least one of the test ports (e.g., both of the test ports) may be omitted. While the stuffing box includes the flapper assembly in the illustrated embodiment, in other embodiments, the flapper assembly may be omitted.

In certain embodiments, the stuffing box may include a primary seal support ring positioned below the primary seal(s) (e.g., alone or in combination with the flapper assembly). Downward movement of the primary seal support ring along the longitudinal axis may be blocked by the internal shoulder of the primary housing. Accordingly, the primary seal(s) may be compressed between the secondary housing and the primary seal support ring. In certain embodiments, the primary seal support ring may be disposed between the primary seal(s) and the flapper carrier of the flapper assembly along the longitudinal axis. However, in other embodiments, the flapper assembly may be omitted, and the primary seal support ring may be disposed between the primary seal(s) and the internal shoulder along the longitudinal axis. In certain embodiments, the primary seal support ring may not be rigidly coupled to the primary housing (e.g., the primary seal support ring may be inserted into the primary housing and moved to the installed position without restriction during assembly of the stuffing box). However, in other embodiments (e.g., in embodiments in which the flapper assembly is omitted), the primary seal support ring may be coupled to the primary housing by suitable connection(s) (e.g., a threaded connection, pinned connection(s), fastener connection(s), etc.). In such embodiments, the internal shoulder of the primary housing may be omitted. Furthermore, in certain embodiments, the primary seal support ring may be omitted.

In the illustrated embodiment, a second annular ring 88 is positioned between the primary seal(s) 74 and the flapper carrier 82 of the flapper assembly 80/primary seal support ring. The second annular ring 88 is configured to function as a bushing between the primary seal(s) and the flapper carrier 82/primary seal support ring. The second annular ring 88 may be formed from any suitable material (e.g., brass, a polymeric material, etc.), and the second annular ring may be formed from any suitable number of circumferential elements (e.g., 1, 2, 3, 4, or more). Furthermore, while the stuffing box 36 includes a single second annular ring 88 in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer second annular rings (e.g., 0, 2, 3, 4, or more). For example, in certain embodiments, the second annular rings may be omitted. In such embodiments, a seal engagement surface of the flapper carrier/primary seal support ring may be formed from a material (e.g., polymeric material, etc.) to enable the flapper carrier/primary seal support ring to function as a bushing.

In the illustrated embodiment, an annular gasket 89 (e.g., o-ring, etc.) is disposed between the flapper carrier 82 of the flapper assembly 80 and the primary housing 42 along the radial axis 60. The annular gasket 89 is configured to block oil from flowing through the interface between the flapper carrier 82 and the primary housing 42. While a single annular gasket 89 is disposed between the flapper carrier 82 and the primary housing 42 in the illustrated embodiment, in other embodiments, more or fewer annular gaskets (e.g., 0, 2, 3, 4, or more) may be disposed between the flapper carrier and the primary housing. For example, in certain embodiments, the annular gasket may be omitted. Furthermore, in the illustrated embodiment, an annular gasket 90 (e.g., o-ring, etc.) is disposed between the primary housing 42 and the secondary housing 44 along the radial axis 60. The annular gasket 90 is configured to block oil from flowing through the interface between the primary housing 42 and the secondary housing 44. While a single annular gasket 90 is disposed between the primary housing 42 and the secondary housing 44 in the illustrated embodiment, in other embodiments, more or fewer annular gaskets (e.g., 0, 2, 3, 4, or more) may be disposed between the primary housing and the secondary housing. For example, in certain embodiments, the annular gasket may be omitted.

As previously discussed, one or more secondary seals 91 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more) are disposed within the secondary housing 44. Each secondary seal 91 has an annular shape and extends about the internal circumference of the secondary housing 44, and each secondary seal is configured to engage the polish rod at the end of the series of polish rods. In addition, each secondary seal 91 may be formed from any suitable material (e.g., polymeric material, rubber, etc.) and configured to expand along the radial axis 60 in response to compression along the longitudinal axis 50. In certain embodiments, each secondary seal 91 is formed as a single annular piece configured to extend about the internal circumference of the secondary housing 44. However, in other embodiments, at least one secondary seal may be formed from multiple circumferential elements that collectively form the annular secondary seal. As illustrated, the secondary seal(s) 91 are disposed between the cap 52 and a base 92 of the secondary housing 44. The fastener(s) 54 are configured to drive the cap 52 along the longitudinal axis 50 toward the secondary seal(s) 91, thereby driving the cap 52 to compress the secondary seal(s) 91 between the cap 52 and the base 92 of the secondary housing 44. For example, a target torque may be applied to each fastener 54 to establish a target compression of the secondary seal(s) 91 (e.g., in which the target compression establishes a target radial contact force between the secondary seal(s) and the polish rod).

Because the secondary seal(s) are compressed by linear movement of the cap, bushing(s)/ring(s) that may be positioned between the secondary seal(s) and the components that compress the secondary seal(s) may be obviated, thereby reducing the height of the stuffing box. However, in certain embodiments, such as the illustrated embodiment, a third annular ring 93 is positioned between the secondary seal(s) 91 and the cap 52 along the longitudinal axis 50. The third annular ring 93 is configured to function as a bushing between the secondary seal(s) 91 and the cap 52. The third annular ring 93 may be formed from any suitable material (e.g., brass, a polymeric material, etc.), and the third annular ring may be formed from any suitable number of circumferential elements (e.g., 1, 2, 3, 4, or more). Furthermore, while the stuffing box 36 includes a single third annular ring 93 in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer third annular rings (e.g., 0, 2, 3, 4, or more). Furthermore, in certain embodiments, such as the illustrated embodiment, a fourth annular ring 94 is positioned between the secondary seal(s) 91 and the base 92 of the secondary housing 44 along the longitudinal axis 50. The fourth annular ring 94 is configured to function as a bushing between the secondary seal(s) 91 and the base 92 of the secondary housing 44. The fourth annular ring 94 may be formed from any suitable material (e.g., brass, a polymeric material, etc.), and the fourth annular ring may be formed from any suitable number of circumferential elements (e.g., 1, 2, 3, 4, or more). Furthermore, while the stuffing box 36 includes a single fourth annular ring 94 in the illustrated embodiment, in other embodiments, the stuffing box may include more or fewer fourth annular rings (e.g., 0, 2, 3, 4, or more).

In the illustrated embodiment, the primary housing 42 has one or more apertures 95 extending from an interior cavity 96 of the primary housing 42 to the exterior surface 58 of the primary housing 42 along the radial axis 60. As illustrated, the interior cavity 96 is positioned between the primary seal(s) 74 and the secondary seal(s) 91. Accordingly, oil that bypasses the primary seal(s) 74 may flow into the interior cavity 96 and through the aperture(s) 95. While two apertures 95 are shown in FIG. 4, the primary housing 42 may have any suitable number of apertures distributed about the circumferential axis 66 of the stuffing box 36 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more).

In addition, as previously discussed, the adapter ring 62 is disposed about the primary housing 42 and aligned with the aperture(s) 95 along the longitudinal axis 50. As illustrated, the port 64 extends through the adapter ring 62 along the radial axis 60, and the adapter ring 62 is configured to rotate relative to the primary housing 42 about the longitudinal axis 50, thereby enabling the port 64 to be positioned at any desired location along the circumferential axis 66. In the illustrated embodiment, a plug 68 is disposed within the port 64. However, the plug 68 may be removed to facilitate fluidly coupling the port to a suitable device (e.g., oil collection container, oil sensor(s), etc.). As illustrated, at least one annular gasket 98 (e.g., 1, 2, 3, or more) is disposed below the aperture(s) 95 along the longitudinal axis 50, and at least one annular gasket 100 (e.g., 1, 2, 3, or more) is disposed above the aperture(s) 95 along the longitudinal axis 50. In the illustrated embodiment, each gasket is at least partially disposed within a respective recess in the primary housing. Additionally or alternatively, at least one gasket may be at least partially disposed within a respective recess in the adapter ring. Each gasket is engaged with the adapter ring 62 and the primary housing 42. Accordingly, any oil that bypasses the primary seal(s) 74 and flows through the aperture(s) 95 is directed through the port 64 (e.g., to the oil collection container, to the oil sensor(s), etc.), thereby enabling an operator or an automated system to detect the quantity/rate of oil flow through the primary seal(s). If the quantity/rate of oil flow through the primary seal(s) 74 is greater than a threshold quantity/rate, the compression of the primary seal(s) may be increased or the primary seal(s) may be replaced.

As previously discussed, the primary housing 42 has a shoulder 102 configured to engage the adapter ring 62 to align the adapter ring 62 with the aperture(s) 95. The shoulder 102 is configured to block movement of the adapter ring 62 in a downward direction along the longitudinal axis 50. In addition, the retaining ring 70 is engaged with a recess 104 in the primary housing 42 to block upward movement of the adapter ring 62 along the longitudinal axis 50. Because the port 64 may be positioned at any suitable location along the circumferential axis 66, a line that extends from the port 64 (e.g., to the oil collection container, to the oil sensor(s), etc.) may be positioned to avoid other components surrounding the stuffing box 36, thereby facilitating formation of the wellhead.

In the illustrated embodiment, the adapter ring 62 has the port 64 disclosed above (e.g., primary port) and a secondary port positioned on an opposite radial side of the adapter ring from the primary port 64. While the adapter ring includes one primary port and one secondary port in the illustrated embodiment, in other embodiments, the adapter ring may include more or fewer primary ports (e.g., 0, 2, 3, 4, or more) and/or more or fewer secondary ports (e.g., 0, 2, 3, 4, or more). Furthermore, in embodiments in which the adapter ring has multiple ports (e.g., one or more primary ports and/or one or more secondary ports), each port may be positioned at any suitable location along the circumferential axis of the adapter ring. While the stuffing box 36 includes the adapter ring 62 in the illustrated embodiment, in other embodiments, the adapter ring may be omitted. In such embodiments, one or more lines (e.g., extending to the oil collection container, the oil sensor(s), etc.) may be fluidly coupled to respective aperture(s) extending through the primary housing. In addition, while the primary housing has one or more apertures for monitoring oil that bypasses the primary seal(s) in the illustrated embodiment, in other embodiments, the apertures extending through the primary housing may be omitted.

While the secondary housing is coupled to the primary housing by a threaded connection in which the external threads of the secondary housing are engaged with the internal threads of the primary housing in the illustrated embodiment, in other embodiments, the secondary housing may be coupled to the primary housing by another suitable threaded connection. For example, in certain embodiments, the primary housing may have external threads, and the secondary housing may have internal threads. In such embodiments, an engagement portion of the secondary housing positioned radially inward from the body of the primary housing may compress the primary seal(s) via rotation of the secondary housing relative to the primary housing while the internal threads of the secondary housing are engaged with the external threads of the primary housing. Furthermore, while the primary and secondary housings are coupled to one another by a threaded connection in the embodiments disclosed above, in certain embodiments, the primary and secondary housings may be coupled to one another by another suitable connection. For example, the primary and secondary housings may be coupled to one another via a fastener connection, via a cap that engages the primary housing via a threaded connection, or via another suitable type of connection. In such embodiments, the secondary housing may compress the primary seal(s) via a force applied by the connection, or another suitable element (e.g., compression ring, cap, etc.) may be employed to compress the primary seal(s).

While only certain features have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f). 

1. A stuffing box for an artificial lift system, comprising: a primary housing having threads; at least one primary seal disposed within the primary housing, wherein the at least one primary seal is configured to engage a polish rod; a secondary housing having threads; and at least one secondary seal disposed within the secondary housing, wherein the at least one secondary seal is configured to engage the polish rod; wherein the threads of the secondary housing are configured to engage the threads of the primary housing to couple the secondary housing to the primary housing, and the secondary housing is configured to compress the at least one primary seal via rotation of the secondary housing relative to the primary housing while the threads of the secondary housing are engaged with the threads of the primary housing.
 2. The stuffing box of claim 1, comprising a cap coupled to the secondary housing and configured to compress the at least one secondary seal.
 3. The stuffing box of claim 2, comprising a plurality of fasteners configured to couple the cap to the secondary housing and to drive the cap toward the at least one secondary seal.
 4. The stuffing box of claim 1, wherein the primary housing has at least one aperture extending from an interior cavity of the primary housing to an exterior surface of the primary housing, and the interior cavity is positioned between the at least one primary seal and the at least one secondary seal.
 5. The stuffing box of claim 4, comprising an adapter ring disposed about the primary housing and aligned with the at least one aperture along a longitudinal axis of the stuffing box, wherein the adapter ring is configured to rotate relative to the primary housing, and the adapter ring has a port extending radially through the adapter ring.
 6. The stuffing box of claim 1, wherein the secondary housing has at least one flat surface configured to interface with a tool to enable the tool to drive the secondary housing to rotate relative to the primary housing.
 7. A stuffing box for an artificial lift system, comprising: a primary housing having internal threads; at least one primary seal disposed within the primary housing, wherein the at least one primary seal is configured to engage a polish rod; a secondary housing having external threads, wherein the external threads of the secondary housing are configured to engage the internal threads of the primary housing to couple the secondary housing to the primary housing, and the secondary housing is configured to compress the at least one primary seal via rotation of the secondary housing relative to the primary housing while the external threads of the secondary housing are engaged with the internal threads of the primary housing; at least one secondary seal disposed within the secondary housing, wherein the at least one secondary seal is configured to engage the polish rod; and a cap coupled to the secondary housing and configured to compress the at least one secondary seal.
 8. The stuffing box of claim 1, comprising a plurality of fasteners configured to couple the cap to the secondary housing and to drive the cap toward the at least one secondary seal.
 9. The stuffing box of claim 1, wherein the primary housing has at least one aperture extending from an interior cavity of the primary housing to an exterior surface of the primary housing, and the interior cavity is positioned between the at least one primary seal and the at least one secondary seal.
 10. The stuffing box of claim 9, comprising an adapter ring disposed about the primary housing and aligned with the at least one aperture along a longitudinal axis of the stuffing box, wherein the adapter ring is configured to rotate relative to the primary housing, and the adapter ring has a port extending radially through the adapter ring.
 11. The stuffing box of claim 10, wherein the primary housing has a shoulder configured to engage the adapter ring to align the adapter ring with the at least one aperture along the longitudinal axis of the stuffing box.
 12. The stuffing box of claim 11, comprising a retaining ring configured to engage a recess in the primary housing and to block movement of the adapter ring away from the shoulder along the longitudinal axis.
 13. The stuffing box of claim 7, wherein the primary housing has external threads configured to engage corresponding internal threads of a pumping tee to couple the stuffing box to the pumping tee.
 14. The stuffing box of claim 7, wherein the secondary housing has at least one flat surface configured to interface with a tool to enable the tool to drive the secondary housing to rotate relative to the primary housing.
 15. The stuffing box of claim 7, comprising a flapper assembly disposed within the primary housing, wherein the flapper assembly comprises a flapper carrier and a flapper pivotally coupled to the flapper carrier, the flapper is biased toward a closed position, and the flapper is configured to engage the flapper carrier while in the closed position to substantially block oil flow through the stuffing box.
 16. The stuffing box of claim 15, wherein the primary housing has an internal shoulder configured to engage the flapper carrier to block movement of the flapper carrier along a longitudinal axis of the stuffing box.
 17. A stuffing box for an artificial lift system, comprising: a primary housing; and at least one primary seal disposed within the primary housing, wherein the at least one primary seal is configured to engage a polish rod; a secondary housing coupled to the primary housing; at least one secondary seal disposed within the secondary housing, wherein the at least one secondary seal is configured to engage the polish rod; and an adapter ring disposed about the primary housing, wherein the primary housing has at least one aperture extending from an interior cavity of the primary housing to an exterior surface of the primary housing, the interior cavity is positioned between the at least one primary seal and the at least one secondary seal, the adapter ring is aligned with the at least one aperture along a longitudinal axis of the stuffing box, the adapter ring is configured to rotate relative to the primary housing, and the adapter ring has a port extending radially through the adapter ring.
 18. The stuffing box of claim 17, wherein the primary housing has a shoulder configured to engage the adapter ring to align the adapter ring with the at least one aperture along the longitudinal axis of the stuffing box.
 19. The stuffing box of claim 18, comprising a retaining ring configured to engage a recess in the primary housing and to block movement of the adapter ring away from the shoulder along the longitudinal axis.
 20. The stuffing box of claim 17, wherein the secondary housing is coupled to the primary housing via a threaded connection. 